Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a first image in a sequence of a display screen or portion thereof with transitional graphical user interface showing my new design according to a first embodiment;

FIG. 2 is a second image thereof;

FIG. 3 is a third image thereof;

FIG. 4 is a fourth image thereof;

FIG. 5 is a first image in a sequence of a display screen or portion thereof with transitional graphical user interface showing my new design according to a second embodiment;

FIG. 6 is a second image thereof;

FIG. 7 is a third image thereof; and,

FIG. 8 is a fourth image thereof.

The outermost broken line showing of the display screen or portion thereof is for environmental purposes only and forms no part of the claimed design.

The remaining broken lines in the figures depict portions of the transitional graphical user interface which form no part of the claimed design.

The appearance of the transitional graphical user interface sequentially transitions between the images shown in FIGS. 1-4 and FIGS. 5-8 , respectively. The process or period in which one image transitions to another forms no part of the claimed design. 

CLAIM I claim the ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 